Phased array beam steering control with phase misalignment correction

ABSTRACT

A system for remotely controlling the phase of active antenna elements in a phased array that has the capability of correcting the inherent phase misalignment of each individual antenna element within the array. Beam azimuth and elevation signals are fed into an appropriate arithmetic unit by a radar signal processor. Roll, yaw and pitch signals are fed into the same arithmetic unit by an inertial navigation system. The arithmetic unit, using the information from the inertial navigation system and the radar signal processor, computes the phase shift required for each individual antenna element in order to point the radar beam in the desired direction. To compensate for inherent phase alignment in the system, an antennule position and alignment store feeds a predetermined alignment factor for each antennule into the arithmetic unit. The arithmetic unit then adds or subtracts the alignment factors from the respective computed phase angles. All the calculated phase angles are then sent to the control circuitry of the antenna array. A Csc2 beam phase shift store provides for generation of a Csc2 beam at the array.

United States Ptent Campanella Feb. 29, 1972 [54] PHASED ARRAY BEAMSTEERING CONTROL WITH PHASE MISALIGNMENT CORRECTION Primary ExaminerCarlD. Quarforth Assistant Examiner-J. M. Potenza Attorney-R. S. Sciasciaand Thomas 0. Watson, Jr.

[72] Inventor: Matthew J. Campanella, Hammonton, NJ. 7 ABSTRACTAssigneei The United Sums of Amerim as A system for remotely controllingthe phase of active antenna represented y the Secretary of the Navyelements in a phased array that has the capability of correcting theinherent phase misalignment of each individual antenna [22] Flled 1970element within the array. Beam azimuth and elevation signals [21] Appl.No.: 18,029 are fed into an appropriate arithmetic unit by a radarsignal processor. Roll, yaw and pitch signals are fed into the samearithmetic unit by an inertial navigation system. The [52] [1.8. CI...343/l00 SA, 343/854 arithmetic unit using the information from theinertial h 7/03 tion system and the radar signal processor, computes theof Search R, pha e shift required for each individual antenna element inorder to point the radar beam in the desired direction. To [56]References Cited compensate for inherent phase alignment in the system,an antennule position and alignment store feeds a predetermined UNITEDSTATES PATENTS alignment factor for each antennule into the arithmeticunit. 3 324 452 6/1967 Brightman et a1. ""343/100 SA The arithmetic unitthen adds or subtracts the alignment fac- 3,482244 12/1969 Gadenne n "343 00 S A tors from the respectlve computed phase angles. All the calcu-3 478 358 1 1/1969 Tri on 343/100 S A lated phase angles are then sentto the control circuitry of the g antenna array. A Csc beam phase shiftstore provides for 1 generation ofaCsc beam at the array.

7 Claims, 7 Drawing Figures T0 REC RIER 222;: i

L STORE STORE RPE N U L ES 'Q coat l ot i J, 1 IN THE SET REGISTERREGISTER ROLL sm, cos TRANSFER YAW sm cos 26 2a 29 a PITCH sm, cos DATAAZ. sm, cos WF ADDRESS mg r RECEIVING s FT ,2 ELGSINICOS 27 l DRIVERS LREGISTER POLARIZATION REC-GATE 36 ANTENULE Asses wa LINE REGISTER MODE46 47 37 SYNC CONTROL TIMING a 40 CONTROL L 19g L CPOUNLTSlE SL 2PQLAR|ZAT|QN /-/a /7 /5 I Q P DISCRMWATCD REGISTER J t l I CONTROLPULSES LINE POLARTIQATION DIGITAL CONTROL CONTROLLER l6 MONOPULSE ERRORsmmu. RADAR susmu. l i i PROCESSOR ANTENULE PATENTEBFIEB as me SHEET 1OF 3 zl A y BEAM POINTING ANGLES m APERTURE COORDINATES' GEOMETRY OF THEMONOPULSE ANGLE ERROR SIGNAL WITH RESPECT TO THE X INERTIAL AND APERTURECOORDINATES F IG. 2

ADDRESS RESET 9/ TRANSFER 94 SHIFT 93 SHIFT I /L L\ A CONTROL illlllI|||ll||l| ||l m5? 1 i I l i F1660 i I A RESET AND GAIN92 RESIET AND 96POLARIZATION TRANSFER ADDRESS /0/ /6'\2 DATA TRANSFER DATA AND {PREINVENTOR.

' MATTHEW J CAMPA/VELLA 11M aux).

ATTORNEY PHASE!) Y BEAM STEERING CONTROL WITH PHASE MTSALIGNMENTCORRECTION STATEMENT OF GOVERNMENT INTEREST The invention describedherein may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the paymentof any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention pertains to radar antennasystems and more specifically to microwave energy radar antenna systemsof the phased array type. VHF or lower UHF antenna arrays for radarsystems are well known in the art. By applying a predetermined relativeamplitude and phase to the signal applied to each of the antennaelements within the array, the desired radiation pattern can be obtainedfrom the combined action of all the elements. The relative phases of thesignals received by the antenna elements within the array determine theposition of the main beam. If the relative phases do not vary, theentire radiation pattern is fixed. If steering of the beam is desired,varying the phase relationship between the elements of the array willvary the position of the main beam.

A two-dimensional planar array of antenna elements has been found to beone of the most versatile antenna arrays available since it is possibleto cause such an array to generate a variety of beams by varying thephase relationship between the individual antenna elements of the array.The beams generated by a two-dimensional planar array may be scanned byapplying to each element the necessary phase shift required to positionthe beam in the desired direction at each point in time. Anindependently controlled phase shifter is attached to each element toprovide the proper phase shift. These phase shifters may be controlledseparately or by groups, such as controlling the rows and columns of thearray in groups, which is called parallel-parallel control.

One of the major drawbacks in a phased antenna array is the difficultyof maintaining phase stability under less than laboratory conditions.Since the system itself will introduce phase changes, it becomesnecessary that the phase changes introduced by the transmission lines,amplifiers, mixers and other components in the array be constant andnegligibly small. In order to achieve this ideal, the environment withinwhich the radar operates must be maintained at constant conditions andthe voltages applied to the amplifiers must not vary.

Several approaches have been tried to get satisfactory operation in lessthan ideal conditions. One approach has been the use of aservo-controlled loop to maintain constant the phase shift through themajor networks of the array. Another method would be to provide a vemierphase shifter in the signal path of each antenna element and have eachvemier individually set during the alignment procedures of the array.The servoloop system previously mentioned is very complex, expensive anddifficult to maintain whereas the use of vernier phase shifterscomplicates the active antenna element electronics. Use of vemier phaseshifters presents a physical problem of where to locate the alignmentcontrol since there is not much room on the element itself for mountingcontrols that are easily accessible when the antennule is in place inthe array.

SUMMARY OF THE INVENTION The instant invention resolves the inherentphase misalignment problem economically and with the least amount ofcomplexity. In an electronically scanned phased antenna array, therequired respective phase shifts are stored in an antennule position andalignment store and are fed to a central arithmetic unit when required.The central arithmetic unit receives desired azimuth and elevation datafrom a radar signal processor. The arithmetic unit, using the roll,pitch and yaw information from an inertial navigation system, andantennule coordinates obtained from the antennule position and alignmentstore, computes the phase shift required for the respective antennule topoint the beam in the desired direction. It then compensates thecomputed phase shift for the inherent phase misalignment of eachantennule system. After being so computed and compensated, the phaseshifts are sent to the antennules via fan out and driver circuits. Toroute the correct phase shift to each antennule, an antennule address isassociated with each computed phase shift and both are sent out seriallyover data and address signal lines to the addressed antennule. If theparticular antennule is being addressed, it is recognized by an addressdecode gate. When this gate is activated, it will cause the phase shiftinformation which follows the address information on the signal line tobe entered into the receiving shift register of the addressed antennule.In normal operation, all the antennules of an array are loaded insequence. When they have all been loaded, an address code, to which allthe antennules respond is sent out by the arithmetic unit. Upon receiptof this code, all the phase shifts are simultaneously transferred fromthe respective receiving shift registers to the respective phase shiftregisters. The latter register drives the phase shifter in theantennule. Therefore, it can be seen that by adding or subtracting therespective phase shift required to correct for the inherent phasemisalignment of each antennule system in the central arithmetic unitbefore the phase shift is distributed to the various antennules, avemier phase shift control on the antennule proper is not necessary andthe whole system is simplified and more reliable.

OBJECTS OF THE INVENTION An object of this invention is to provide phaseshift beam steering control for an antenna array that automaticallycorrects for inherent phase misalignments.

A further object of this invention is to provide phase shiftbeam-steering control for an antenna array that automatically correctsfor inherent phase misalignments and is compatible with roll, pitch andyaw stabilization of the entire array.

A still further object of this invention is to provide phase shiftbeam-steering control for a planar antenna array that automaticallycorrects for inherent phase misalignments and is compatible withgeneration of a diversity of beam patterns.

Another object of this invention is to provide phase shift beam-steeringcontrol for a planar antenna array that facilitates beam scanning andautomatically corrects for inherent phase misalignments as theindividual array elements are phase shifted.

Yet another object of this invention is to provide phase shiftbeam-steering control for a planar antenna array that facilitates beamscanning and automatically corrects for inherent phase misalignments asthe individual array elements are individually phase shifted.

Another object of this invention is to provide phase shift beam-steeringcontrol for a corporate fed, active aperture planar antenna array thatfacilitates beam scanning and automatically corrects for inherent phasemisalignments as the individual array elements are individually phaseshifted.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a vector illustration of thebeam pointing vector and the angles that are utilized in computing itsdirection;

FIG. 2 is a vector illustration of the angular error created by therolling motion of the antenna structure;

FIG. 3 is a block diagram of the overall phased array beam pointing andscanning system;

FIG. 4 is a diagram partially in block and partially in schematic formwhich illustrates the data-receiving and implementation controlcircuitry of each antennule in the array;

IIII a! FIG. is a diagram partially in block and partially in schematicform which illustrates the control signal receiving and implementationcontrol circuitry of each antennule in the array;

FIG. 6a illustrates the type of control pulses sent to the controlcircuits of the antennules; and

FIG. 6b illustrates the data and address pulses sent to the informationcircuits of the antennules.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The phase shiftbeam-steering control function and embodiment of the instant inventionwill be illustrated in a corporate' fed, active aperture, antenna array.A corporate-fed array, as is well known in the art, implies that thedistribution of microwave energy to the array elements is by shieldedtransmission lines which have equal length paths from the input port toall the elements of the array. An active aperture antenna (antennule)array, as is well known in the art, implies that the individual arrayelements contain active devices for generating or amplifying microwaveenergy. Choice of a corporate-fed, active aperture, array does notpreclude the use of other forms of arrays such as the space-fed typeusing a refractive lens array or a reflective array, either with activeantenna elements or passive antenna elements. The planar, activeaperture corporate fed, antenna array, contemplated for use with thepresent invention is capable of generating the two basic beam shapesrequired for all radar modes, the Csc 0Cos 0 beam which is used formapping modes, and the pencil beam which is used for all other modes.

Use of a trihex antennule as the antenna element is contemplated withthis invention. The trihex antennule comprises three hexagonal elementsgrouped together to form a linear trihex package. A hexagonal elementwas selected to obtain maximum radiation area and to maintain thedesired centerto-center spacing between the antennules. The groupingtogether of three hexagonal-shaped antenna elements into a linear trihexpackage results in a reduction of the number of connectors that arerequired to connect the antennules to the beam-steering controlcircuitry. The present invention functions equally effectively with anyother antennule arrangement.

A phased antenna array such as described above requires beam-steeringand control systems to direct and control the radiated beam formed bythe array. Since an array involves hundreds and perhaps even thousandsof individual radiating elements whose individual phases must becontrolled, the problem of controlling the beam quickly takes ongigantic proportions. This is particularly true in an airborneenvironment where weight and space limitations further complicate theproblem.

The direction and pointing control of the beam is based on the fact thatthe far field radiation pattern can be determined by use of the fouriertransform of the excitation in the antenna aperture:

cost? cosy ii ,x i

This equation gives the phase of each radiating element in the array forthe desired pointing direction. The equation needs to be solved for eachantennule very time the beam is repositioned.

Two possible methods for stabilizing the antenna beam in space may beused, the electronic and the electromechanical. The electromechanicalmethod introduces certain distinct disadvantages in that the antennaaperture, along with most of its supporting electronics, must be free torotate. Electronic stabilization on the other hand requires less spaceand is appreciably lighter along with the additional factor of havinghigher reliability. Computations required to keep the radiated beamfixed in space as an aircraft, for example, rotates are basically thoseof a three-dimensional angular coordinates conversion. The functionalrelationships between the aircraft angular motion and beam pointingangles, in aperture coordinates, are given by:

CosB= Sin 6 Sin 4) Cos E [Cos ill Cos A Sin i1: Sin A] +Cos CosE[CosubCosA-Sin illCosA] +Cos0SinSinE (501.311)

Cos y= Sin 0 Cos d) Cos E [Cos illCos A Sin ll; Sin A] Sin 4) Cos E [SinilvCos A Cos ibSin A] +Cosd Cos0SinE (Eq.3b) where:

,3, beam pointing direction angles in aperture coordinates 111 yaw angle6 pitch angle (1) roll angle A azimuth position of beam in inertialreference frame E elevation position of beam in inertial reference frameThe functional relationship between the aircraft motion and thebeam-pointing angles in aperture coordinates can be seen by looking atFIG. 1 where the y--z plane is the plane of the aperture. The X axis istherefore the broadside direction. Angles a, [3 and 'y are the directionangles of the beam-pointing vector [3,. Angle 3 is the azimuth angle andangle 4 is the elevation angle of the beam-pointing vector.

Equations 3a and 3b give the beam-pointing direction in aperturecoordinates for any desired azimuth and elevation position in inertialcoordinates. The angles calculated are carried through and utilized bythe beam-pointing control system of the invention as direction cosinesrather than radian measures, since that is the way they appear in theequation for the antennule phase shift; this simplifies the computationsrequired.

If the antenna aperture is not roll gimbal stabilized then the azimuthand elevation error signals do not form a tracking mode with respect tothe inertial coordinate system but rather with respect to the aperture(vehicle) coordinate system. Conceivably the tracking loops could bearranged to be executed in aperture coordinates. But, an inversecomputation would have to be implemented as part of this approach inwhich the inertial position of the beam is computed from its directioncosine in aperture coordinates. The equations involved are the inversesof equations 3a and 3b. Since the solution of these equations have to beimplemented for regular positioning of the beam in standing modes, itwould be advantageous if they could be used again for monopulse trackingand thereby avoid implementing their inverses.

This can be done by initially converting the monopulse error signals toinertial coordinates, using a simpler computation. and performingtracking in inertial coordinates. FIG. 2 shows the geometry of themonopulse angle error signal with respect to the inertial and aperturecoordinates. From this figure it is readily seen that:

E'E eE Cos 4: t eA Sin (11 (Eq. 4a) e' eE Sin d: EA Cos (Eq. 4b) where:

e angular error E5 ekfvanon error i .aperture coordinates A azimutherror I eA azimuth error 7 roll angle The error signals given by theabove two angular error equations 4a and 4b are applied to the initialazimuth and elevation beam pointing control circuits so as to repositionthe beam and drive it to zero, but at the same time retain the beamposition in inertial coordinations without further computations.

An appropriate phase angle, previously determined, is added to eachantennule to obtain a csc beam pattern. These phase shifts are inaddition to those required to point the beam in a given direction. Phaseshift values will be predetermined in the computer rather thanrepeatedly calculating them by use of some form of curve. In theequation used, the symetry of the phases required to obtain the csc 9beam is such that the phase shifts are the same per each row ofantennules in the array. Consequently, a different phase shift is onlyrequired for each row, which considerably reduces the storagerequirement.

In addition to pointing the beam, it is sometimes desired that thebeam-pointing control system be used for remotely controlling thepolarization of the radiated signal and the receiving gain of theantennule aperture. Signals for both of these functions would be sent atthe beginning of an operating mode and need not be repeatedly updatedevery time the beam is stepped. But, provision must be made in a centralunit for generating it and in the antennule for receiving and holdingthis control information. Two bits of storage are required in theantennule for controlling the polarization state. Four polarizationstates exist, vertical, horizontal, left circular and right circular.

Control of the antennule-receiving gain is used to obtain signal shadingacross the aperture. The gain is varied as a function of radial distancefrom the aperture origin with a functional relationship of the form CosX.

Another requirement of the beam-pointing control circuitry is that ofproviding means for correcting the inherent phase misalignment of theantennules in the aperture. This basically amounts to adding anadditional phase shift to the beam-point ing phase shift to compensatefor the fact that the azimuth signal path through the manifold variesslightly from antennule to antennule. The amount of phase shift to beadded, which is stored within the beam-pointing control circuitry, isexperiinently determined for each antennule during alignment of theradar beam.

The foregoing discussion of the basic mathematical and logicmanipulations necessary to accomplish the function of a phased arraybeam-steering control system will now be implemented by reference to aspecific organization of the abovementioned mathematical and logicmanipulations to accomplish a contemplated embodiment of a phased arraybeamsteering control system which will control the phase shift of theantennules within the array and thereby control the direction of thebeam.

Referring to FIG. 3, the functional blocks to the right of thedashed-line labeled antennule show the functions contained in a typicalantennule of which there would be hundreds or perhaps even thousands inone array. The functional blocks on the left side of the dashed linelabeled antennule show those functions that are performed for many orall of the antennules by centralized circuitry.

The signals indicating the direction in which it is desired to point thebeam, originate in digital controller 15 of FIG. 3 which is part of astandard radar signal processor. A radar application is used forillustrative purposes because this is a primary application of phasedarray antennas. The beam direction indicating signal is sent by digitalcontroller 15 over lines i2 and 13 to arithmetic unit 22. The beamdirection indicating signal is in the form of sines and cosines of thedesired azimuth and elevation angles. This form of the signal is chosenfor convenience to save computation time in arithmetic unit 22. Had thedigital controller output been in terms of the angle directly in degreesof radian measure, arithmetic unit 22 "Gina would have to convert theminto sines and cosines since that is the functional form which entersinto the beam-pointing equations, previously noted.

The pointing angle designated by digital control 15 is in inertialcoordinates. When the antenna array is movable and unstabilized theseinertial angles have to be converted to angles using the antenna planesas a reference. A coordinate conversion using roll, yaw and pitch anglesfrom an inertial navigation system, not shown, is performed inarithmetic unit 22. The inertial angles of azimuth and elevation fromthe digital controller are converted to angles with respect to theantenna plane. The specific mathematical equations 3a and 3b, toaccomplish this function were mentioned above.

Having established the pointing angles with respect to the array plane,in aperture coordinates, the next operation in arithmetic unit 22involves determining the phase shift required for each antennule toobtain the desired pointing angle of the beam. The basic beam-pointingequation, Equation 2, is used to compute the required phase shift foreach antennule. The coordinates of each antennule in the array arestored in antennule position and alignment store 24 from which they areretrieved in sequence. These coordinates address the calculated phaseshifts.

Antennule position and alignment store also provides the alignment phaseshift required to compensate for phase shifts introduced by the variousradiofrequency paths. As far as the radiation field of the array isconcerned, it makes no difference whether the phase shift of a specificantennule is caused by a difference in the azimuth path lengths or by acalculated phase shifting in the phase shifter. If the deviations of theradiofrequency path length with respect to a nominal value is determinedby experimentation for a particular antennule, this value can then beadded or subtracted from every phase shift computed for that particularantennule. This would automatically, thereby, eliminate the path phaseshift error. The experimentally determined phase shifts are stored inantennule position and alignment store 24 with the associated coordinatepositions. When a phase shift for an antennule at a particular arrayposition is computed, the associated phase shift error is simply addedor subtracted therefrom.

The phase shifts for all the antennules are computed in sequence inarithmetic unit 22. As each is computed it is sent to the addressedantennule and stored there while the phase shifts for the rest of theantennules are being computed. Conceivably, the phase shifts could beinitially stored in a central more and then distributed to theantennules after all the computations had been made. This has thedisadvantage, however, that wider bandwidth data lines and drivers areneeded for a given antenna scan rate than is required when the phaseshifts are sent to the antennules individually.

After being computed, the phase shift information is sent to theantennule by way of a serial data and address lines 26 and 27. All theantennules are attached to line 29 which is connected to lines 26 and 27by means of fan-out and drivers 28. In addition to the phase shiftinformation these lines also carry, in serial form, the address of theantennule for which the data is intended. Appropriate circuitry isprovided in the antennule to recognize when the data on line 29 isintended for it. A single data and address line is used instead of aplurality in order to reduce the number of signal leads going to eachantennule.

Another signal lead going to each antennule is the control pulses line30 of FIG. 3. It carries timing and control signals from control unit119 to the antennule. The signals received control and direct thesignals appearing on data and address line 29.

The relationship between the signals on data and address line 29 andcontrol pulses line 3% and some pomible waveforms are shown in FIG. 6.The signals appearing on control pulses line 30 are used to command suchcontrol functions as reset, shift and address transfer. Since it is notdesirable to use separate lines for each separate command because of thelarge number of antennules used in an array, all the sigials are put ona single line and identifying characteristics such as differences inamplitude and/or spacing are employed to separate them. This method ofsignal transmission is commonly known in the art as multiplexing. Forexample, the shift pulses 93 and 95 which are used to shift incomingdata on data and address line 29 into the shift register 35 haveone-half the amplitude of reset pulses 91. The reset signal 91 consistsof three full amplitude pulses while address transfer signal 94 consistsof two pulses. Reset and gain transfer signal 92 and reset andpolarization transfer signal 96 have a different polarity than the othersignals. These are only a few of the possible characteristics that mightbe used to identify and separate the various control signals coming overthe control pulses line.

The antennule address and phase shift data appear in sequence on thedata and address line 29. Normally, address data 101 of FIG. 6b whichcontains as many bits as is required to individually address all theantennules in the array follows, in time, the reset signal on controlpulses line 30. The particular antennule that is addressed will thenadmit phase shift data I02 that follows address bits 101. The format ofthe data bits may be return to zero or not return to zero, at thedesigners discretion. They are shown as not return to zero in FIG. 6bsince this requires less bandwidth and would therefore be preferrable inthis embodiment.

Referring now to FIG. 3 and the right-hand side of the dashedlinelabeled antennule which illustrates the antennule section of the phasedarray beam-steering control system, the address data appearing on thedata and address line 29 is shifted into antennule address shiftregister 36 if the address corresponds to that of the particularantennule to which this shift register belongs. Antennule address shiftregister 36 upon being addressed will put out a received data signalwhich opens a gate in the input of the receiving serial register 35.This allows the phase shift data that follows the address data to beentered into receiving serial register 35 where it is stored until allthe antennule receiving serial registers in the array have been loaded.When all the registers have been loaded with phase shift information, aspecial address transfer command is sent to all the antennules. Uponreceiving it all the antennule address shift registers, such as 36, putout a transfer signal over line 48 which transfers the phase shift datain the receiving shift registers, such as 35, to the antennule phaseshift register, such as 38. The phase shift registers, such as 38, drivethe phase shifters within each antennule. When this occurs, the antennabeam steps to its new pointing direction.

It is sometimes desirable to vary the radiofrequency gain and/or thepolarization of the signal radiated by the antennule aperture. Thesignals to vary the gain and polarization can be handled over the samesignal lines as used for the basic phase shift information, either byadding this to the basic phase shift or by using separate data wordsthat are transmitted at different times than the phase shift data. Thelatter method which has the advantage of requiring less computation timeis illustrated in FIG. 3. This scheme also requires additional controlsignals such as reset and gain transfer signals 92 and reset andpolarization transfer signals 96 which are illustrated in FIG. 6. Thecommand signals, when radiofrequency gain or polarization control isused, originate in digital controller 16 of the radar signal processorand flow to arithmetic unit 22 by way of lines 1 8 and 21. The signalsflow through arithmetic unit 22 and to driver circuit 28 where they areappropriately modified in format before being sent to the antennule.

The right-hand side of the dashed line in FIG. 3 also illustrates theorigin of the control pulses on control pulses line 30. Digit controllerprovides to control circuit 19 mode and synchronizing data by way oflines I8 and 17 from which control circuit 19 determines appropriatetiming and control signals. These signals are sent out over line 20 tofan-out and driver circuits 28 which distribute them to all theantennules by means of a control pulse line such as 30.

In some modes of operation it is desired that the antenna beam be a Cscfl variation rather than the normal pencil beam.

5 To obtain this beam a particular pattern of phase shift data has to begiven to the antennule array above that required to point the antennabeam. This data is stored in Csc e beam phase shift store 23 and is afactor determining the phase shift data computed for each antennule inarithmetic unit 22.

If the antenna aperture is not gimbal roll stabilized, the monopulseangle error created by aperture roll must be compensated by a monopulseerror signal 16 which is introduced into digital controller 15. Thismonopulse error signal is calculated within the radar signal processoras explained in conjunction with the description of FIG. 2.

FIGS. 4 and 5 show in detailed block diagram form a possible way ofimplementing the functions performed in the antennule as shown in FIG.3.

FIG. 5 shows a scheme for separating out the various controls signalsthat appear on control pulse line 30 and corresponds to control pulsediscriminator 37 of FIG. 3. The first step in the process is separatingthe positive control pulses from the negative ones. This is accomplishedby polarity sensing and shaping circuits 50. Following the path ofnegative pulses 92 and 96, shown in FIG. 6a, first, the first negativepulse to occur fires one-shot 51 whose output (on the negative goingedge) sets flip-flop 53. The first occurring negative pulse is alsoapplied to the trigger input of flip-flop 53 but is overridden by theoutput of one shot 51. The succeeding input negative pulses triggerflip-flop 53 through two steps if the group contains three pulses orjust one step if the group contains only two. Therefore, depending onthe number of pulses in the train, the gain transfer gate 54 orpolarization transfer gate 55 will be primed by the output of flip-flop53. The second oneshot 52 is triggered by the trailing edge of theoutput of the first one shot 51. The output pulse duration of the firstone shot 51 is adjusted so that it is longer in duration than either thegroup of three of two negative pulses triggering flip-flop 53.Consequently, when one shot 52 is fired by the trailing edge on thefirst pulse, its output pulse is channeled to the gain transfer line 44or the polarization transfer line 43 in aceordance with the state offlip-flop 53. Flip-flop 53, of course, has been set by the number (twoor three) of negative pulses in the group.

Returning to the polarity sensing and shaping circuit 50 let us considerthe positive-going pulses that appear out of the right-hand side. Bypassing them through thresholding circuits 57, the full-amplitude pulsescontaining reset and address transfer signals are separated from thehalf-amplitude shift pulses. However, mixed in with these shift pulsesare the bases of the double-amplitude pulses which must be separatedout. This is accomplished by using and gate 63 in conjunction with theoutput of one shot 58. Shown to the right of thresholding circuit 57,the output of one-shot 58 is adjusted to be equal to or slightly betterthan the duration of the sets of reset or address transfer pulses. Byusing this output to inhibit and gate 63, only those pulses whichcorrespond to the original shift pulses get through the gate, and are soindicated on output line 45.

To distinguish between the groups of two or three positive pulses, thesame logical operation as was used for the negative-going pulses isused. This is seen by glancing at the righthand side of FIG. 5. Gates 61and 62 in conjunction with flipflop 64. one shot 59 and one-shot 58perform the same functions as one-shot 51 in conjunction with one-shot52, flip-flop S3 in conjunction with gates 54 and 55, in distinguishingbetween the groups containing two or three positive pulses.

The various control pulses generated by the logic circuitry of FIG. 5are used to control the shift register transfer gate and stores in FIG.4. The latter are used to receive and hold the incoming address andphase shift data appearing on data and address line 29. Address bitsappearing on data and address line 29 are shifted serially into theaddress serial register 65 by phase shift command pulse generated by thecircuitry of FIG. 5 at output line 45. Phase shift register 65 is shownas having a bit storage length of six bits for illustrative purposesonly, for it can actually be any length that is required. These sameaddress bits do not enter receiving serial register 76 because receivegate 75 is normally closed. Address decode gate 67 which is attached toaddress serial register 65 senses when the received address is that ofthe particular antennule. When it is, flip-flop 70 is set causingreceive gate 75 to open the path to receiving serial registers 76. Thisallows the data bits which follow the address bits on the data andaddress line 29 to enter the receiving serial register 76. Had theparticular antennule not been addressed, receive gate 75 as well asshift pulses gate 74 would have remained closed and the receiving serialregister 76 would have been undisturbed.

It is therefore obvious that by this scheme data may be sequentiallysent to all the antennules in an array. The data is held in a receivingserial register 76 until transferred to the appropriate store, such astransmit phase shift register 79, receive phase shift register 80, gaincontrol register 86, or polarization register 87, by the transfer pulsesgenerated in the control pulses discriminator of FIG. 5, or by the phaseshift transfer pulse generated from the address serial register 65. Thephase shift transfer pulse is generated when address serial register 65receives a step decode word which is recognized by all the antennuleswhich have a step decode gate 66. Thus, the transfer of phase shift datawithin the antennule is basically under remote control.

Separate transmit phase shift and received phase shift registers areshown in FIG. 4 because in some applications different phase shifts aredesired when transmitting energy then when receiving it. In certainapplications when this is not desired nor necessary, only one phaseshift store register need be provided.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings.

What is claimed is:

l. A phase shift beam-steering control system for an antenna arraycomprising:

an array of antenna elements;

a plurality of phase shifter means equal in number to said antennaelements and connected to a corresponding antenna element for causing aphase shift in signals applied to said array;

antenna control means connected to said phase shifter means forcontrolling the sequence and distribution of phase shift data toindividual phase shifter means;

an arithmetic unit connected to said control means and responsive tobeam-steering input data, which comprises beam-pointing data andalignment data, for calculating beam phase shift data for each antennain said array and delivering it to said antenna control means;

an alignment store connected to said arithmetic unit for deliveringalignment data to said arithmetic unit;

said alignment data includes for each antenna element (a) itscoordinates in said array and (b) phase shift compensation data; and

a system controller means connected to said arithmetic unit fordelivering beam-pointing data to said arithmetic unit.

2. The phase shift beam-steering control system of claim 1 wherein saidarithmetic unit is further responsive to roll, pitch, and yaw data forsaid array, said arithmetic unit taking such data into consideration incalculating beam phase shift data.

3. The phase shift beam-steering control system of claim 1 furthercomprising a beam pattern data store connected to said arithmetic unitfor supplying said arithmetic unit with beam pattern data; and

wherein said arithmetic unit is further responsive to beam pattern datawhen calculating beam phase shift data; and wherein said antenna arrayis a planar antenna array.

4. The phase shift beam-steering control system of claim 1 wherein saidsystem controller means delivers beam-pointing data in a predeterminedorder to said arithmetic unit causing it to calculate and deliver phaseshift data to said antenna control means that instructs said antennacontrol means to provide a scanning pattern for the beam generated bysaid array.

5. The phase shift beam-steering control system of claim 1 wherein saidarithmetic unit calculates the beam phase shift data for each individualantenna element and prefixes such data with an identifying address; and

wherein said antenna control means comprises logic circuitry individualto each active element responsive to its identifying address to processthe beam phase shift data transmitted by said arithmetic unit.

6. The phase shift beam-steering control system of claim 5 wherein saidalignment store delivers predetermined alignment data to said arithmeticunit for each individual antenna element, the alignment data beingprefixed by the appropriate active antenna element address.

7. The phase shift beam-steering control system of claim 6 wherein saidalignment store provides alignment data for the receive mode of systemoperation and for the transmit mode of system operation, if the twomodes require different alignment data for each antenna element.

nun-t:

1. A phase shift beam-steering control system for an antenna arraycomprising: an array of antenna elements; a plurality of phase shiftermeans equal in number to said antenna elements and connected to acorresponding antenna element for causing a phase shift in signalsapplied to said array; antenna control means connected to said phaseshifter means for controlling the sequence and distribution of phaseshift data to individual phase shifter means; an arithmetic unitconnected to said control means and responsive to beam-steering inputdata, which comprises beampointing data and alignment data, forcalculating beam phase shift data for each antenna in said array anddelivering it to said antenna control means; an alignment storeconnected to said arithmetic unit for delivering alignment data to saidarithmetic unit; said alignment data includes for each antenna element(a) its coordinates in said array and (b) phase shift compensation data;and a system controller means connected to said arithmetic unit fordelivering beam-pointing data to said arithmetic unit.
 2. The phaseshift beam-steering control system of claim 1 wherein said arithmeticunit is further responsive to roll, pitch, and yaw data for said array,said arithmetic unit taking such data into consideration in calculatingbeam phase shift data.
 3. The phase shift beam-steering control systemof claim 1 further comprising a beam pattern data store connected tosaid arithmetic unit for supplying said arithmetic unit with beampattern data; and wherein said arithmetic unit is further responsive tobeam pattern data when calculating beam phase shift data; and whereinsaid antenna array is a planar antenna array.
 4. The phase shiftbeam-steering control system of claim 1 wherein said system controllermeans delivers beam-pointing data in a predetermined order to saidarithmetic unit causing it to calculate and deliver phase shift data tosaid antenna control means that instructs said antenna control means toprovide a scanning pattern for the beam generated by said array.
 5. Thephase shift beam-steering control system of claim 1 wherein saidarithmetic unit calculates the beam phase shift data for each individualantenna element and prefixes such data with an identifying address; andwherein said antenna control means comprises logic circuitry individualto each active element responsive to its identifying address to processthe beam phase shift data transmitted by said arithmetic unit.
 6. Thephase shift beam-steering control system of claim 5 wherein saidalignment store delivers predetermined alignment data to said arithmeticunit for each individual antenna element, the alignment data beingprefixed by the appropriate active antenna element address.
 7. The phaseshift beam-steering control system of claim 6 wherein said alignmentstore provides alignment data for the receive mode of system operationand for the transmit mode of system operation, if the two modes requiredifferent alignment data for each antenna element.